At some point in The Hobbit, while the Company is travelling, Balin walks alongside Bilbo and they start chatting. This will help to establish Balin as Bilbo's best friend amongst the Dwarves. They end up discussing what they want to do with themselves once they get their share of Smaug's treasure (reminding the audience of the film's purpose). Balin mentions that he'd like to take a colony of Dwarves and restore the abandoned underground city of Khazad-dûm to its former glory.

There's no need for Balin to mention this in the scene at the very end of the second film where he and Gandalf visit Bag End – The Hobbit shouldn't end on such a downbeat note reminding us that there is plenty of death and failure to come.